This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 39 |
| 6 | 409 |
| 7 | 4687 |
| 8 | 62822 |
| 9 | 945250 |
| 10 | 15999616 |
| 11 | 300150210 |
| 12 | 6198330586 |
| 13 | 139779046596 |
| 14 | 3420083177362 |
| 15 | 90241503643208 |
| 16 | 2554721759776914 |
| 17 | 77240614583288344 |
| 18 | 2484170781778551036 |